1. Field of the Invention
The present invention relates to lighting fixtures and more specifically, to a LED lighting fixture, which uses a light guide board having a reflective layer covering a surface and having a portion protruding into the light guide board to guide light from LEDs so as to increase the angle of illumination and to provide a uniform lighting effect having an enhanced brightness without multi-image and flashing.
2. Description of the Related Art
The history of lamp extends for long. Since the invention of lamp to produce light, it greatly improves the living style of people. Nowadays, a variety of lighting fixtures of different outer appearances have been disclosed for different purposes. Because of heavy market demand, improvements on function as well as on application should never stop.
Despite of different design changes, conventional lighting fixtures use a lamp bulb or lamp tube to produce light. These conventional lighting fixtures have the common drawbacks of high consumption of electric energy and production of heat. The production of heat greatly not only shortens the service life of the lighting fixture but also increases the ambient temperature. Further, a daylight lamp causes a flashing problem that is harmful to the eyes.
Nowadays, LEDs (light emitting diodes) have been intensively used in lighting fixtures to substitute for conventional lamp bulbs and tubes for the advantages of low power consumption and long service life. Further, because LEDs do not contain mercury, using LEDs for lighting fixture brings no harm to environment.
However, LEDs may be too dim in bright light situations because of its unidirectional lighting feature. Therefore, a LED lighting fixture has the drawback of limited angle of illumination. To overcome this problem, multiple LEDs may be arranged together and set in different angles. However, this arrangement greatly complicates the fabrication of the lighting fixture and will also increase the cost. Further, a lighting fixture constructed according to this arrangement may produce multiple images, not practical to substitute for conventional daylight lamps.
Taiwan Patent Publication No. M306666 discloses a light guide structure for lighting fixture, which is an invention of the present inventor. According to this design, the light guide structure comprises a light guide board made of a transmissive material having a clear transmissive layer, and a reflective layer covered on the back side of the light guide board. The reflective layer has an arched convex portion on the middle (see claim 7). The light guide structure is used with a lateral light source to construct a lighting fixture that increases the angle of illumination, provides a uniform lighting effect with enhanced brightness, and eliminates the multi-image and flashing problems of conventional daylight lamps.
However, the design of the arched convex portion of the reflective layer still has a limitation in reflection. Therefore, there is still a room for improvement.